Contribution and Reservation

ECM, P-1, P+1

Look for prime factors by GMP-ECM first. Refer to the section "Efforts by ECM". Not only ECM but also P-1/P+1 may be helpful.

GNFS

Use GGNFS and/or Msieve if GMP-ECM cannot find a factor. The SNFS difficulty of this composite number is 187.04-digit and the GNFS difficulty is 124.51-digit. GNFS must be faster than SNFS. It will take about 4 CPU-days to factor this composite number on 64-bit Opteron-2600MHz.

1. Put factMsieve.pl to which $GGNFS_BIN_PATH and $NUM_CPUS were modified properly in the working directory 12227_186.
2. Put the following polynomial file 12227_186.poly in there too.
3. And then, run "perl factMsieve.pl 12227_186".

# Murphy_E = 1.527969e-10, selected by Jeff Gilchrist
n: 32078518654571540845797512642206599349593095836079225190577270470910073536954138148253200950675967955631430085910975641067001
Y0: -1009485039378964555479762
Y1: 34586793430301
c0: -17904376591451933662120893415715
c1: -74790035409910668870168534
c2: 703760013490898711547
c3: -873055532883078
c4: -13484026660
c5: 30600
skew: 277484.61
type: gnfs
# selected mechanically
rlim: 7000000
alim: 7000000
lpbr: 27
lpba: 27
mfbr: 52
mfba: 52
rlambda: 2.5
alambda: 2.5

*1 These parameters were not fully adjusted. The approximate expressions which were used for making the parameters are: d=log10(n); time=10^(d/21-4)[hours]; rlim=round(3*10^(d/37+3)); lpbr=floor(d/18+21); mfbr=floor(d/5+28); rlambda=floor(d/26+21)/10;

See also

• How to contribute your factors

The efforts by ECM to find small factors of this 125-digit composite number so far are as follows. According to the reports, unknown prime factors of this composite number are probably 35-digit or more. Please report your efforts by ECM. (Anonymous reports are not acceptable)